Abstract: The characteristics of the multi-gimbal structures were analyzed based on the kinematics theory of LOS stabilization and tracking, and the selection principle for gimbal structures was given. Using the PIOGRAM method, a typical two-axis gimbal structure, three axes two-gimbal structure and two axes four-gimbal structure were discussed. The problems such as gimbal lock and the blind area of tracking were expatiated by the relationship of angle and rate. The requirements for different platforms and target motions were obtained and they could be used for selecting proper gimbal structure for specific application. The method is also applicable to other multi-axis structure and can be used for analyzing geometric.